The present invention relates to a housing for an electric appliance and especially to the grounding of components of this housing. To ensure that electrical appliances can be operated safely, metal parts which can be touched by a user and which conduct voltage while the appliance is operating or for which there is the possibility of them being able to conduct a voltage as a result of a fault, must be grounded. For blank metal parts this can be done by pressing the parts, e.g. screwing them firmly onto a grounding conductor. Such a grounding conductor can for example be a wire connected to ground potential of an ac mains power socket or any electrically-conductive part of the housing which is connected directly or indirectly electrically-conductively to such a wire.
With metal parts which are enameled or coated in some other way to make them electrically insulated such press contact is not sufficient to reliably establish a conductive connection.
To establish a reliable conductive contact to an enameled panel or one which is coated to provide some other form of electrical insulation, a screw with a sharp-edged profile can be used which, inserted into a hole in this panel, cuts its own thread in the hole and in doing so penetrates the insulating coating. It is difficult however to achieve the required operational safety with such a connection, since, to enable the screw to cut the thread, without a disproportionate torque having to be exerted on it, the panel must be quite soft or quite thin, with the result that only a slight load can be imposed on the connection made by the screw.